## Copyright (C) 2016 Jeremiah Orians
## This file is part of stage0.
##
## stage0 is free software: you can redistribute it and/or modify
## it under the terms of the GNU General Public License as published by
## the Free Software Foundation, either version 3 of the License, or
## (at your option) any later version.
##
## stage0 is distributed in the hope that it will be useful,
## but WITHOUT ANY WARRANTY; without even the implied warranty of
## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
## GNU General Public License for more details.
##
## You should have received a copy of the GNU General Public License
## along with stage0.  If not, see <http://www.gnu.org/licenses/>.

# :start
0D00002E	# FALSE R14 ; R14 will be storing our current address
E0002D2F0118	# LOADUI R15 $end ; We will be using R15 for our stack


# ;; Main program functionality
# ;; Reads in Tape_01 and writes out results to Tape_02
# ;; Accepts no arguments and HALTS when done
# :main
# ;; Prep TAPE_01
E0002D201100	# LOADUI R0 0x1100
42100000	# FOPEN_READ
# ;; Prep TAPE_02
E0002D201101	# LOADUI R0 0x1101
42100001	# FOPEN_WRITE
# ;; Perform main loop
# :main_0
E0002D211100	# LOADUI R1 0x1100 ; Read from tape_01
42100100	# FGETC ; Read a Char
# ;; Check for EOF
E000A0100000	# CMPSKIPI.GE R0 0
3C000010	# JUMP @main_1
# ;; Process that byte
E0002D0F0022	# CALLI R15 @dehex
# ;; Increment address
E1000FEE0001	# ADDUI R14 R14 1
# ;; Get next byte
3C00ffdc	# JUMP @main_0
# :main_1
# ;; Close up as we are done
E0002D201100	# LOADUI R0 0x1100 ; Close TAPE_01
42100002	# FCLOSE
E0002D201101	# LOADUI R0 0x1101 ; Close TAPE_02
42100002	# FCLOSE
FFFFFFFF	# HALT


# ;; Dehex functionality
# ;; Accepts byte in R0
# ;; Prints address every 4th byte
# ;; Alters R0
# ;; Returns to whatever called it
# :dehex 5a
0902001F	# PUSHR R1 R15 ; Preserve R1
0902000F	# PUSHR R0 R15 ; Save byte until after address
E100B00E0003	# ANDI R0 R14 3 ; Get mod 4 of address
E0002D211101	# LOADUI R1 0x1101 ; We want it on TAPE_02
E000A0200000	# CMPSKIPI.E R0 0 ; if not zero
3C000028	# JUMP @dehex_0 ; Skip placing address
# ;; Prepend new line
E0002D20000a	# LOADUI R0 10 ; First print line feed
42100200	# FPUTC ; Write it
# ;; Write out address
0900040E	# COPY R0 R14 ; Prep for call
E0002D0F0030	# CALLI R15 @hex32 ; Let it handle the details
# ;; Write out : char
E0002D20003a	# LOADUI R0 58 ; Prep
42100200	# FPUTC ; Write it
# ;; Write out tab
E0002D200009	# LOADUI R0 9 ; Prep
42100200	# FPUTC ; Write it
# :dehex_0 a0
0902800F	# POPR R0 R15 ; Restore byte received
E0002D0F003a	# CALLI R15 @hex8 ; Use a subset
E0002D200020	# LOADUI R0 32 ; Prep for writing space
42100200	# FPUTC ; Write it
0902801F	# POPR R1 R15 ; Restore R1
0D01001F	# RET R15 ; Return to caller


# ;; hex32 functionality
# ;; Accepts 32bit value in R0
# ;; Require R1 to be the device to write the results
# ;; Returns to whatever called it
# :hex32 bc
0902000F	# PUSHR R0 R15
E0002D600010	# SR0I R0 16 ; Do high word first
E0002D0F0004	# CALLI R15 @hex16
0902800F	# POPR R0 R15
# :hex16 d0
0902000F	# PUSHR R0 R15
E0002D600008	# SR0I R0 8 ; Do high byte first
E0002D0F0004	# CALLI R15 @hex8
0902800F	# POPR R0 R15
# :hex8 e4
0902000F	# PUSHR R0 R15
E0002D600004	# SR0I R0 4 ; Do high nybble first
E0002D0F0004	# CALLI R15 @hex4
0902800F	# POPR R0 R15
# :hex4 f8
E100B000000f	# ANDI R0 R0 0x000F ; isolate nybble
E1000F000030	# ADDUI R0 R0 48 ; convert to ascii
E000A0400039	# CMPSKIPI.LE R0 57 ; If nybble was greater than '9'
E1000F000007	# ADDUI R0 R0 7 ; Shift it into 'A' range of ascii
42100200	# FPUTC ; Print char
0D01001F	# RET R15 ; Get next nybble or return if done
# ;; Where we are putting our stack
# :end 118